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Faran uses the maximum alpha value in order to avoid underestimation which is ~ 62.98 km/ms in our case. Also Faran calculates alpha based on PingER historical data to all the world regions and in this study we only used the North American PingER sites. Looking at the frequency histogram of alpha for the SLAC landmark to North American target sites it is seen that this is a reasonable maximum value.
Europe
We selected 3 landmarks in Europe for our study ( CERN_Switzerland, ICTP_Italy, UK_Warrington). They were chosen because they were more reliable as compared to other landmarks. We pinged a set of known geographical targets in Europe. The coordinates of these sites were obtained from PingER database. We also calculated the physical distances
between the targets and the landmarks. It appeared that all the hosts were within 65 ms of the three landmarks and 96.15 % were within 50 ms.
Conclusion
References
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\[1\] A region may be different then a geographical region |